Single-crystalline vanadium dioxide actuators

Actuators that convert other forms of energy to mechanical energy have attracted extensive interest for their critical applications in microelectromechanical systems and miniature robotics. Recently, it is discovered that vanadium dioxide (VO2)"based microscale bimorph actuators demonstrate comprehensive superiority of actuation performances, taking the good of the giant theoretical power density (7 J cm−3) and ultrafast response (∼picosecond) of crystalline VO2, while they still suffer from the intrinsic shortcomings of complex structures. Here, "single"crystalline VO2 actuators" (SCVAs) that have unique self"bending behavior upon temperature change are reported. This is realized by facilely and precisely controlling the phase structures via lateral stoichiometry"engineering in VO2 nanobeams at the nanoscale level. These SCVAs exhibit remarkable actuation performances and admirable stability, which are equivalent or even superior to the reported VO2"based conventional bimorph actuators. It is noteworthy that the gradual, reversible, and predictable bending of SCVAs enables a precise actuation control of related mechanics, such as the quantitative wind detector and thermal micromechanical claw. This work demonstrates the possibility of this strategy to enable single crystalline actuators excellent performance by internally lateral and gradual strain"engineering.